斜流泵叶轮水力径向力的数值模拟与试验验证（英文）

Numerical simulation and experimental validation on hydrodynamic radial force of mixed-flow pump impeller

该文采用数值分析法研究了斜流泵叶轮的水力径向力变化规律,通过数值模拟准确地预测了斜流泵的水力性能,扬程预测误差在4.4%以内。通过数值分析获得了斜流泵叶轮的瞬态水力径向力数据,均匀进口条件下,叶轮的瞬态水力径向力均值几乎为零。对瞬态水力径向力进行傅里叶分析,获得其在频域内的分布,结果显示,当工况从0.6倍设计流量点变至0.4倍设计流量点时,1倍和4倍轴频下的径向力突然增大,叶轮的水力不平衡和动静干涉中的叶片通过激励增强了上述频率下的水力径向力数值。流场分析显示,在小流量工况时,叶轮与导叶体之间的回流涡旋完全占据了泵内流道空间。进一步的压力脉动分析证实,在小流量工况下,动静干涉中的叶片通过激励显著增大了叶轮与导叶之间测试点的压力脉动幅值。

This paper presents a numerical investigation of hydrodynamic radial force of mixed-flow pump, through validations and CFD simulations under several flow rates, the global performances of the mixed-flow pump is accurately predicted with RNG k-ε turbulence model, the head prediction error is less than 4.4% under all the operational conditions. The recirculation between the impeller and diffuser dominates the flow passage at part-load conditions, the pressure amplitude at 4 times shaft frequency was bigger than other frequencies, it increased sharply while the flow rate changed from 0.6 to 0.4 nominal flow rate, these demonstrated that the rotor-stator impeller blade passing excitation strengthened the pressure amplitudes of points between the impeller and diffuser under part-load conditions. The transient hydrodynamic radial forces of impeller present a periodicity change with time, the average value of transient radial force is close to zero under a uniform inflow condition. The FFT spectrum analysis of radial forces demonstrated that the amplitude of hydrodynamic radial forces under part-load conditions are much higher than nominal condition, especially at 1 time and 4 times shaft frequency, these phenomena are mainly attributed to the hydraulic imbalance of rotor, rotor-stator impeller blade passing excitation, rotor-stator blade interaction excitation and etc. Based on the analysis above, it is concluded that the recirculation flow pattern under part-load conditions has a significant influence on pressure fluctuation and hydrodynamic radial force.